Effect of long chain branching on the properties of polyethylene synthesized via metallocene catalysis
Bibliographic record
Abstract
In this research, the effect of long chain branching (LCB) and polymerization conditions on thermal, mechanical, and rheological properties of polyethylene synthesized via a metallocene polymerization was studied. The LCB was varied in the range of 0.64–1.14 per 10 4 atoms of C. 13 C NMR spectra showed that the distributions of both short as well as long chain branches in the polymer backbone chain are influenced by polymerization conditions. The increase in ethylene pressure leads to rise in polymer yield, catalyst activity, molecular weight, and narrowing of molecular weight distribution. In contrast, the increase of polymerization duration results in broadening of MWD and a decrease in catalyst activity. In addition, the influence of frequency and LCB on dynamic shear and extensional melt rheology has been reported. The polymer crystallization was discussed in light of Avrami model and modified Hoffman-Lauritzen theory. LCB promoted the transport of chain segments but retarded the nucleation in polyethylene crystallization. The tensile strength decreased with the increase in LCB content. The different macroscopic properties were correlated to LCB content.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".